Memos
A memo is not a reference. A reference is complete and you read into it; a memo carries one technique and is meant to be absorbed and then ignored. That difference decides the whole layout — fewer items, larger, with the thing you actually do made the biggest object on the page.
The memos here are the first chords on guitar and ukulele, coffee ratios by brewing method, the matcha drinks, converting imperial units in your head, the flexbox properties, and where a change is sitting in Git.
They are for the wall directly in front of you — beside the instrument, over the kettle, next to the screen. Not for a shelf.
SPRING AND NEAP TIDES
the Earth–moon–sun geometry that makes the tides swing — after NOAA
CPR AND CHOKING
the 2025 American Heart Association algorithms, step by step — bystander, trained rescuer, and choking at three ages
THREE HAND STITCHES
backstitch · running stitch · whipstitch — what shows on the face and what the thread does underneath
HANDWASHING
five steps, and the 20 seconds that actually matter
STAIN REMOVAL
five stain classes and the method for each — per publication H.E. 2-840 of the University of Kentucky Cooperative Extension
BINARY COUNTING
five doubling cards build every number from 0 to 31 — exactly the way every computer counts
THE EXIT STATUS
One byte from a command to the shell: what the standard assigns in it, what it leaves to the system — and why “128 + signal number” is nowhere in the standard
FILE DESCRIPTORS
Three levels between a number and a file: what two numbers of one description share, what two descriptions do not — and where the offset lives
FILE LOCKS
A lock lies on a range of bytes, it has two different kinds of owner, and it guards no byte at all
FILE PERMISSIONS
Nine bits in three triads, three special bits — and why r and x on a directory are different powers
CSS FLEXBOX
main axis and cross axis · which property belongs to which
GIT WORKING AREAS
four areas · the command that moves code between them
![FILENAME EXPANSION: *, ?, […]](/api/img/cmsp2eg3h001q2dpdnyxkt8mu)
FILENAME EXPANSION: *, ?, […]
A leading dot and a slash disappear only in filename expansion: the same pattern “*” is seen by case, but not by expansion itself
HERE-DOCUMENTS
The body reaches the command as a single word, and one quote in the delimiter decides whether it arrives as typed
IFS AND FIELD SPLITTING
Two kinds of delimiter: white ones merge into one, non-white ones each cut on their own — and the same value gives one field or four
LOGIC GATES
Seven digital-logic symbols — and how to build six of them from a single element, NAND
THE FLAGS OF OPEN()
FIVE flags of creating a file — and why O_CREAT|O_EXCL is not a faster check but a check and a creation joined into one indivisible act
${…}: FOUR MODIFICATIONS
The colon asks about emptiness too: in the column of the empty variable it changes the answer four times out of four, and in the other two columns none
${…}: TRIMMING BY PATTERN
The sign says from which end to cut and doubling it says how much: from the same path the same pair of patterns takes away either one character or fifteen
THE ORDER OF REDIRECTIONS
Redirections are done from left to right, and “2>&1” copies where the output points at that very moment: the file first — and it holds two lines; the copy first — one
QUOTING IN THE SHELL
29 characters named by the standard, 4 ways to take the meaning off them — and the 3 characters where double quotes stop
read: A LINE INTO VARIABLES
The last variable takes the whole rest of the line, inner spaces and all; without -r the backslash disappears, and a line with no final newline gives status 1 — although the variable is already full
INSERTION SORT
the way cards are ordered in the hand · the trace of one real run
QUICKSORT
splitting around a pivot · the trace of one real run
TWO-CAMERA SPEAKER SETUP
the lighting triangle and where each of the 2 cameras stands · the floor plan from above
THREE-CAMERA SPEAKER SETUP
the lighting triangle and where each of the 3 cameras stands · the floor plan from above
THE SELECT STATEMENT
8 clauses in the order you write them — and the order they take effect in
THE CONDITIONS OF TRAP
FIVE conditions from the standard — EXIT and four signals — and three extensions a conformant shell refuses
THE UMASK
The file mode creation mask: the nine bits it clears, five arguments that name opposite things — and why umask 022 is not chmod 755
WORD EXPANSION
Four steps in a fixed order — and only two of them can change how many fields reach the command
COCKTAIL FORMULAS
five templates by ratio, not fixed recipes — millilitres straight from the official IBA recipes
HOW MUCH COFFEE TO WATER
six methods · weight, grind, time
MATCHA DRINKS
six proportions · grams, millilitres, degrees
WINE TEMPERATURE
neither from the fridge nor from the room — not one of them
BABY-LED WEANING
cutting fruit and vegetables so a baby can feed itself: the shape, the size limit and what is never served
THE BOILED EGG
soft, medium and hard: the minutes on the timer — and the degrees at which the white and the yolk set
THE HAMBURGER
the ratios of the mince and the five steps that decide the result
CAST IRON SKILLET
seasoning in 6 steps and everyday care — after the official Lodge instructions
FIRST FINGER FOODS
the size, the softness and the shape of a piece for a baby who feeds themselves, by the NHS guidance
NEAPOLITAN PIZZA DOUGH
four ingredients in the proportions written into an EU regulation
POUND CAKE
four equal weights — a recipe whose name is its ratio
SOURDOUGH BREAD
the timeline, hydration and grams — per King Arthur Baking’s Naturally Leavened Sourdough Bread
TABLE SERVICE
which side each thing arrives from, in what order the table is served, and what the hand may touch
BARBELL MATHS
the IWF colour code and the plate count: from target weight to each side of the bar, no calculator
THE CLOCK FACE
two hands, twelve numbers — how to read the time
DIVISIBILITY TESTS
what to read in a written number instead of dividing it: the tail, the digit sum and composite divisors
THE DOOMSDAY RULE
the weekday of any date in the Gregorian calendar, worked out in the head in three steps
THE RULE OF 72
the time it takes steady growth to double: the division you can do in your head, how far it misses and why the divisor is what it is